WEST, Texas — The First Baptist Church in the tiny Texas town where a fertilizer plant exploded is still off-limits, so the Rev. John Crowder put folding chairs in a hay pasture and improvised a pulpit on a truck flatbed. At the elementary school, an official carted extra desks and chairs into the only public school campus that is left.

This was Sunday in West. Four days after the blast that killed 14 people and injured 200 others, residents prayed for comfort and got ready for the week ahead, some of them still waiting to find out when — or if — they will be able to go back home.

‘‘We have lost our friends and neighbors. We lost the safety and comfort of our homes,’’ said Crowder, raising his voice over the whirr of helicopters surveying the nearby rubble. ‘‘But as scary as this is, we don’t have to be afraid.’’

The explosion at the West Fertilizer Co. leveled about 50 homes and destroyed an apartment complex and as many as three schools in the city of 2,800 about 80 miles south of Dallas.

Nearly 70 federal and state investigators are still trying to determine what caused the fire that set off the explosion, assistant state fire marshal Kelly Kirstner said. Authorities say there are no signs of criminal intent.

The blast rocketed shrapnel across several blocks and left what Kirstner described Sunday as ‘‘a large crater.’’ A section of the farming town near the crater, including Crowder’s church, is still behind barricades.

One school campus was obliterated, and on the eve of 1,500 students’ return to class for the first time since Wednesday’s blast, Superintendent Marty Crawford said the high school and middle school could also be razed.

Robert Champion, the special agent in charge for the Dallas office of the federal Bureau of Alcohol, Tobacco and Firearms, said investigators plan to enter the crater in the next few days and start digging in search of an explanation.

Slow is the normal way of life in West. But the last several days for many of its residents have melded into an anguishing and frustrating stretch of wait-and-hear, whether about the safety of family and friends, or the fate of their homes.

Six firefighters and four emergency medics were among the dead, and city officials announced that a memorial service would be held Thursday at Baylor University.

Professional organizations and family and friends on Sunday identified four of the first responders who died: brothers Doug and Robert Snokhous, who were both firefighters with the West Volunteer Fire Department; Jerry Chapman, a firefighter with the Abbott Volunteer Fire Department; and Kevin Sanders, who worked with West EMS and another area volunteer fire department.

At least one of the West volunteer firefighters who was killed, Joey Pustejovsky, was a member of St. Mary’s Church of the Assumption.

Firefighters and emergency workers in bright-yellow jackets kneeled in the pews as the Rev. Boniface Onjefu recalled driving toward the fire after the explosion rattled his house.

‘‘I stopped at the nursing home,’’ Onjefu said. ‘‘I noticed a lot of people trapped. I assisted. I prayed with some and held the hands of some that needed comfort.’’

Said Onjefu, ‘‘God heard our prayers and prevented another tank from exploding.’’

Edi Botello, a senior at West High School, is Catholic but stood in a roadside pasture with friend Chelsea Hayes for the First Baptist Church service that drew more than 100 people. ‘‘We needed this,’’ Botello said.

They wore gray ‘‘(hashtag) prayforwest’’ shirts that have become ubiquitous in the town. On the night of the explosion, Botello asked his mother if Hayes, who lived close to the plant, could come over. He said his mom still wonders what might have been if she had said no.

‘‘Every time I close my eyes, all I can think about is the explosion,’’ Botello said. ‘‘People running around. People evacuating. There was one point I couldn’t even talk. I just stuttered.’’

Wendy Castro, a clerk at a nearby Walmart, was among the first allowed back into her home, which sits on the outmost edge of the barricaded area. Broken windows and screen doors twisted off hinges is about the worst damage in her neighborhood.

Among the scorched buildings in the shadow of the plant were the town’s high school and intermediate school.